Interesting Question, No Simple Answer...
, 01:47 AM
The answer is not simple because round ideal cuts are usually priced based on the Rapaport "round" grids, whereas Royal Asschers (and most fancy shapes, for that matter) are priced based on the Rapaport "pear shape" grids. The difference between the round grids and the pear shape grids varies, depending on the color and clarity you compare, so no answer can be exact unless a precise size, color, and clarity are specified.
I had to make a couple of assumptions:
1. The H&A round ideal cut diamond sells at the Rap price.
2. The Royal Asscher price is based on the "suggested margin" list for the Royal Asscher.
Then I inserted the appropriate Rap values into a Microsoft Excel spreadsheet and applied the appropriate multipliers.
As I said, the results depend on what specific size, color, and clarity you are looking for, but to generalize, here is the answer:
In the upper echelons of quality (D-E-F, IF-VVS), the price of a H&A diamond and the Royal Asscher will be about the same.
In middle range stones (G-H-I-J, VS-SI), the Royal Asscher will cost about 10% more.
In the lower qualities (K-L-M, Imperfects), the prices will again be about the same.
Over the whole price grid, from D to M, and from FL to I3, the Royal Asscher will be about 7% more than a comparable H&A ideal cut.
I won't bore everyone by posting the spreadsheets.
Either Jan or Brad of DBOF stated it most clearly in some other thread--you should look at the Royal Asscher cut as comparable to a super-ideal cut diamond. You should not look at it in comparison to a square emerald cut. There really is a vast difference in appearance between the Royal Asscher and a square emerald cut.
Hope this answers the question.
Jay A. Mednikow